Study On The Preparation Process And Hypoglycemic Activity Of Fucoidan From Undaria Pinnatifida

Undaria pinnatifida is a large edible seaweed with high medicinal and economic value.It contains many kinds of active substances,among which fucoidan is one of the most concerned in recent years.Fucoidan is mainly composed of fucose and sulfate groups,and has good pharmacological activities,such as anti-oxidation,anti-tumor and anti-virus.Large-scale preparation of fucoidan from Undaria pinnatifida,especially for the preparation of fucoidan with good biological activity,remains an important bottleneck in the development of fucoidan functional products.In this paper,single factor and response surface experiments were used to optimize the extraction process of fucoidan from Undaria pinnatifida,and the extraction conditions for 100g-grade fucoidan preparation were investigated and the process stability was also evaluted.Then the fucoidan was separated and purified,and the chemical structures of the obtained components were preliminary characterized.Finally,the hypoglycemic activity of the fucoidan was investigated.The research results are as follows:(1)To extract fucoidan from Undaria pinnatifida using water extraction method,single factor experiment was conducted on the extraction time,temperature and material-liquid ratio,then Design Expert 8.0 was used to optimize three-factor three-level response surface experiment based on single-factor test results.Finally,the best extraction condition was obtained(100℃,4 h,1:40).On this basis,a preparation process for extracting 100-grams of fucoidan from Undaria pinnatifida with calcium chloride extraction and water extraction was established,and a total of 820 g of calcium-extracted fucoidan(Up C)and 183.6 g of water-extracted fucoidan(Up W)were prepared with the yields of 1.2% and 1.3%,respectively.The molecular weight curves of different batches of fucoidan obtained by the same extraction method are generally consistent with each other.According to the relevant standards in the 《People’s Republic of China Aquatic Industry Standards(SC/T3404-2012)》,the two processes for fucoidan preparation have good stability.(2)The two fucoidan Up C and Up W were separated and purified by DEAE column purification.Up C and Up W were eluted sequentially with water,0.5 M,1.0 M,and 2.0 M Na Cl solutions,and finally six fucoidans were obtained,which are Up C-1,Up C-2,Up C-3,Up W-1,Up W-2 and Up W-3,and their yields are 25.5%,18.8%,5.0%,32.5%,14.2%,1.69%.Up C-1 is mainly composed of glucose,galactose and fucose,Up C-2 and Up W-1 are mainly composed of mannose,galactose and fucose,Up C-3,Up W-2 and Up W-3 are mainly composed of galactose and fucose.Among them,only Up C-3 contains no uronic acid.As can be seen from the molecular weight spectrum,the molecular weights of Up C-1 and Up W-1 are not uniform,and the molecular weights of Up C-2,Up C-3,Up W-2,and Up W-3 are 510 KDa,425 KDa,764 KDa,766 KDa.It can be analyzed from the FT-IR spectrum that all the sugar chains may contain α-glycosidic bonds.The sulfate group in Up W-1 may be located at the C2 or C3 position of the pyran ring,and the sulfate group of Up C-1 may be vertically connected to-OH at C4.(3)Animal experiments showed that Up W1 can relieve the weight gain,reduce the blood glucose concentration,improve the glucose tolerance and reduce the insulin tolerance of high-fat diet induced metabolic syndrome mice,.The findings highlight the hypoglycemic activity of Up W1.In summary,the present study established a process for preparation of 100-gram grade Undaria pinnatifida fucoidan with hypoglycemic activity,which has laid a certain foundation for the development of seaweed polysaccharide-based functional products.